Unit of lens refractive power, equal to the reciprocal of the lens focus length in meters.

Anti-reflective coatings improve the quality and the value of your lenses. An anti-reflective coating reduces disturbing reflections. It makes your lenses more attractive. And you will experience the most precise, crisp and clear natural vision in a brilliance that is not possible with uncoated lenses.

A misshape of the eye, where vision is blurred by an irregularly shaped cornea. The cornea, instead of being shaped like a sphere, is ellipsoidal (like an egg) and reduces the cornea’s ability to focus light.

Indicates the placement in degrees of the astigmatic lens.

Involves high velocity projectiles. Ballistic eyewear

The curve on the back surface of the contact lens.

Corrective eyewear lenses containing regions with two distinct optical powers. Bifocals are commonly prescribed to people with presbyopia who also require a correction for myopia, hypermetropia, and/or astigmatism.

The width between the lenses on a eyeglass/sunglass frame. Manufacturers typically measure this width at the widest point between the two lenses.

A clouding of the lens of the eye that can lead to blindness.

A small device with sunglass lenses that hooks onto your prescription eyeglasses. Clip-ons